Corrosion resistant antifreeze compositions

ABSTRACT

Corrosion resistant antifreeze compositions consisting essentially of at least one antifreeze fluid having from 1 to 4 carbons inclusive and from 1 to 3 hydroxy groups inclusive and a minor but effective amount sufficient to inhibit corrosion of an alkali metal dialkyl phosphate. The alkali metal dialkyl phosphate can be represented by the formula:   D R A W I N G

United States Patent [72] Inventor Harold McDonald Harrington Park, NJ.[21 Appl. No. 747,093 [22] Filed July 24, 1968 [45] Patented Sept. 21,1971 [73] Assignee Stauffer Chemical Company New York, N.Y.

[54] CORROSION RESISTANT ANTIFREEZE FOREIGN PATENTS 802,347 10/1956GreatBritain Primary Examiner- Leon D. Rosdol Assistant Examiner-D.Silverstein Atlorneys Donald M. MacKay, Robert C. Sullivan, Daniel C.

Block and Paul J. Juettner ABSTRACT: Corrosion resistant antifreezecompositions consisting essentially of at least one antifreeze fluidhaving from 1 to 4 carbons inclusive and from 1 to 3 hydroxy groupsinclusive and a minor but effective amount sufficient to inhibitcorrosion of an alkali metal dialkyl phosphate. The alkali metal dialkylphosphate can be represented by the formula:

wherein R is an alkyl group containing from about 8 to about 16 carbonatoms inclusive, and M is an alkali metal ion.

CORROSION RESISTANT ANTIFREEZE COMPOSITIONS This invention relates toantifreeze compositions and more particularly to corrosion resistantantifreeze compositions useful in automobile cooling systems.

It is well known that the corrosive action of water is particularlytroublesome in automobile cooling systems. This is due to thetemperatures prevailing and to the presence of oxygen and carbon dioxidewhich are introduced by air leaks in the circulatory system or by thenormal aeration process that goes on at the top of the radiator tank.One particular corrosive area is the uppermost portion of the radiator.There the solder joints are preferentially attacked causing waterleakage.

It has now been discovered that corrosion can be substantially reducedat the solder joints by incorporating in the commonly employedantifreeze fluids, a minor but effective amount sufficient to inhibitcorrosion of an alkali metal dialkyl phosphate of the formula:

ll RO-JEf-OR wherein R is an alkyl group containing from about eight toabout 16 carbon atoms inclusive, and M is an alkali metal ion.lllustrative of the alkali metal ions are sodium, lithium and potassium.While ammonium is not truly a member of the alkali metal series, it is aclear equivalent for the alkali metal ions and is generally consideredto be within the term or an equivalent of alkali metals. It is soconsidered in the present case. Sodium ions and ammonium ions arepreferred in the present invention because of their low cost andefficiency. 11- lustrative of the alkyl groups as represented by thesubstituent R are octyl, nonyl, decyl, undecyl, dodecyl, tridecyl,tetradecyl, pentadecyl, hexadecyl and the like. Of these substituentsrepresented by R, decyl has been found to be preferred as such compoundsprovide exceptional corrosion inhibiting properties. Particularlypreferred for similar reasons are the branched decyl groups wherein thedecyl group is derived from a highly branched primary alcohol.

Illustrative and typical of the antifreeze fluids which can be employedare the volatile monohydroxy compounds as well as the nonvolatilepolyhydroxy compounds or mixtures. Preferably the antifreeze fluids willconsist essentially of at least one compound having from one to fourcarbon atoms inclusive, and from one to three hydroxy groups inclusive.Exemplary of the volatile compounds are methanol, ethanol, andisopropanol. Exemplary of the nonvolatile compounds are ethylene glycol,propylene glycol, diethylene glycol, and glycerol.

1n the conduct of this invention, the alkali metal dialkyl phosphate isused in an amount of from about 0.01% to about 5% and preferably fromabout 0. 1% to about 2.0%

If desired, the alkali metal dialkyl phosphates can be used incombination with other inhibitors to include both organic and inorganiccompounds. Among the former are mineral and vegetable oils, theirsulfonated products and amines, amides and mercaptans. The inorganiccompounds include borates, nitrates, nitrites, phosphates, molybdates,arsenites and carbonates. Exemplary of typical inhibitors employedinclude borax, sodium nitrites, sodium mercaptobenzothiazole, sodiumcitrate, triethanoloamine phosphate, hydroquinone. sodium chromate,sodium silicate, sodium sulfite, and sodium benzoate.

The following examples will serve to illustrate the invention and itspreferred embodiments. All parts and percentages in said examples are byweight unless otherwise specified.

EXAMPLE 1 Pursuant to ASTM D 1384-65, a standard antifreeze testsolution was prepared consisting of the following ingredients:

Ethylene glycol 77.5% Propylene glycol 10.0% Dicthylene glycol 5.0%Borax [0H,0) 2.5% Water 5.0

An identical solution was also prepared but for the addition of 0.10% ofsodium didecyl phosphate. Air was introduced into the solutions atapproximately ml./min., the test solutions were maintained at F. andagitated. Pursuant to the aforesaid test, specimens of steel, brass,aluminum, copper and solder were suspended in the test solutions for 2weeks. The air was then shut off, the temperature was reduced to ambient temperature, the agitation was discontinued, and the samples weresuspended for an additional week in the test solutions under staticconditions. At the end of this period, the test samples were removed,cleaned according to the aforesaid method, and the weight losscalculated. The solder samples immersed in the control solutioncontaining no sodium didecyl phosphate exhibited a weight loss of46.30%. The solder samples immersed in the sodium didecyl phosphatecontaining solution exhibited a weight loss of 17.1 1%.

EXAMPLE 2 In accordance with the procedure of Example 1 identicalsolutions are prepared but for the substitution of sodium dioctylphosphate for sodium didecyl phosphate. The results found are in generalagreement with the previous example.

Although the corrosion resistant antifreeze compositions of thisinvention will commonly be employed with tap water, these compositionscan also be employed in the permanenttype package system which normallycontain deionized water.

EXAMPLE 3 Since the alkali metal phosphates form stable emulsion inwater they can be used to advantage as corrosion inhibitors in aqueouscooling systems or in general metal chemical apparatus. These phosphatesare particularly preferred for inhibiting corrosion of ferrous metals,and solder, and can be used in an amount from about 0.01% to about 5%and preferably from about 0.1% to about 1%.

EXAMPLE 4 An 0.1% aqueous solution of sodium didecyl phosphate wasprepared and placed in a 3 litter rectangular container. Sample 1 inch X2 inch solder and milder steel coupons were placed on a plastic disc.The disc was rotated through the test solutions to permit alternateaqueous and air exposure. The samples were rotated for 60 days, thencleaned according to standard techniques (i.e. the solder samples wereimmersed in a boiling solution of 1% glacial acetic acid according toASTM D 1384 and the steel coupons were cleaned by immersion in a boilingsolution of 5% ammonium citrate and cleaned with a brush to removedeposits). The cleaned coupons were weighed and the weight losscomputed. The test was repeated substituting an 0.1% aqueous solution ofsodium chromate for the phosphate solution and the results are comparedin the following table with a control solution containing only water.

The water control was rotated for only 24 days.

Sodium dioctyl phosphate is substituted for sodium didecyl phosphate inthe above test and the results are in general agreement.

What is claimed is:

l. A corrosion resistant alcoholic antifreeze composition consistingessentially of at least one antifreeze fluid having from one to fourcarbons inclusive and from one to three hydroxy groups inclusive and aminor but effective amount sufficient to inhibit corrosion of an alkalimetal dialkyl phosphate of the formula:

wherein R is an alkyl group containing from about eight to about 16carbon atoms inclusive, and M is an alkali metal ion.

2. The composition of claim 1 wherein the alkali metal dialkyl phosphateis present in an amount of from about 0.01% to about 5.0%

' 3. The composition of claim 1 wherein the alkali metal dialkylphosphate is present in an amount of from about 0.1% to about 2.0%.

4. The composition of claim 3 wherein the alkali metal dialkyl phosphateis sodium didecyl phosphate.

5. The composition of claim 3 wherein the alkali metal dialkyl phosphateis sodium dioctyl phosphate.

6. The composition of claim 1 wherein the antifreeze fluid is wherein Ris an alkyl group containing from about eight to about 16 carbon atomsinclusive, and M is an alkali metal ion.

10. The composition of claim 9 wherein the alkali metal dialkylphosphate is present in an amount of from about 0.l0% to about 5%.

11. The composition of claim 9 wherein the alkali metal dialkylphosphate is present in an amount of from about 0.1% to about 1%.

12. A composition of claim 1 wherein the alkali metal dialkyl phosphateis sodium didecyl phosphate.

It is certified that. error appmzars :in the abmvc-jdanilfir-r7 pntuni:and that said Lctttors Patent are hernby corrected as; shown below:

Claim 10, line 2, "0.10%" should be --O. Ol%-.

Signed and sealed this 21st day ofMarch 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Commissioner of PatentsAttesting Officer

2. The composition of claim 1 wherein the alkali metal dialkyl phosphateis present in an amount of from about 0.01% to about 5.0%
 3. Thecomposition of claim 1 wherein the alkali metal dialkyl phosphate ispresent in an amount of from about 0.1% to about 2.0%.
 4. Thecomposition of claim 3 wherein the alkali metal dialkyl phosphate issodium didecyl phosphate.
 5. The composition of claim 3 wherein thealkali metal dialkyl phosphate is sodium dioctyl phosphate.
 6. Thecomposition of claim 1 wherein the antifreeze fluid is a mixture ofethylene glycol, propylene glycol, and diethylene glycol.
 7. Acomposition of claim 6 additionally containing a borax corrosioninhibitor.
 8. A composition of claim 1 wherein the antifreeze fluid is amixture of ethylene glycol, propylene glycol, and diethylene glycol andthe phosphate inhibitor is sodium didecyl phosphate.
 9. A corrosionresistant composition consisting essentially of water and a minor buteffective amount sufficient to inhibit corrosion of an alkali metaldialkyl phosphate of the formula:
 10. The composition of claim 9 whereinthe alkali metal dialkyl phosphate is present in an amount of from about0.10% to about 5%.
 11. The composition of claim 9 wherein the alkalimetal dialkyl phosphate is present in an amount of from about 0.1% toabout 1%.
 12. A composition of claim 1 wherein the alkali metal dialkylphosphate is sodium didecyl phosphate.